Professor Jan Geert Hiddink
Athro

Aelodaeth
Contact info
Room: 406 Westbury Mount Phone: 01248 382864
E-mail: j.hiddink@bangor.ac.uk
Google Scholar, ResearchGate, Twitter
Jan is a professor in the School of Ocean Sciences and specialise in the field of marine benthic ecology. For his PhD he studied the adaptive value of migrations and nursery use for the intertidal bivalve Macoma balthica at the Department of Marine Biology at Groningen University, and he received the Annual VLIZ North Sea Award 2002 from the Flanders Marine Institute (VLIZ) for his PhD thesis. After completing his PhD in 2002, he started a postdoc at Bangor University, where he studied the impact of bottom trawling on the functioning of benthic invertebrate communities. He joined the lecturing staff in SOS in 2006 and was promoted to Reader in 2013. He was awarded a Personal Chair in 2017. JGH has published >95 peer reviewed papers since 2001. His grant capture since 2006 totals over £7M.
His research broadly examines the effect of human disturbance on benthic ecosystems, including fishing and climate change. He has a broad interest in other topics and has been working on research ranging from cattle trampling wader nests on saltmarshes to acoustic monitoring of cetaceans. His research is focussed on gaining a quantitative understanding of the effect of disturbance (such as exploitation and climate change) on the biodiversity and functioning of marine benthic communities, and on how such effects can be mitigated. JGH aims to increase understanding of ecosystem functioning and distribution patterns by comparing empirical data with predictions of ecological models. Much of this research has focused ont the effect of bottom trawling on benthic ecosystems.
Research Areas
- Cyhoeddwyd
Bottom trawl-fishing footprints on the world’s continental shelves
Amoroso, R. O., Pitcher, R., Rijnsdorp, A. D., McConnaughey, R. A., Parma, A. M., Suuronen, P., Eigaard, O. R., Bastardie, F., Hintzen, N. T., Althaus, F., Baird, S. J., Black, J., Buhl-Mortensen, L., Campbell, A., Caterino, R., Collie, J., Cowan, J. H., Durholtz, D., Engstrom, N., Fairweather, T. P., Fock, H. O., Ford, R., Galvez, P. A., Gerritsen, H., Gongora, M. E., Gonzalez, J. A., Hiddink, J., Hughes, K., Intelmann, S. S., Jenkins, C., Jonsson, P., Kainge, P., Kangas, M., Kathena, J. N., Kavadas, S., Leslie, R. W., Lewis, S. G., Lundy, M., Makin, D., Martin, J., Mazor, T., Mirelis, G. G., Newman, S. J., Papadopoulou, N., Posen, P. E., Rochester, W., Russo, T., Sala, A., Semmens, J. M., Silva, C., Tsolos, A., Vanelslander, B., Wakefield, C. B., Wood, B. A., Hilborn, R., Kaiser, M. & Jennings, S., 23 Hyd 2018, Yn: Proceedings of the National Academy of Sciences of the United States. 115, 43, t. E10275-E10282Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Predation of the shelduck Tadorna tadorna on the mud snail Hydrobia ulvae.
Anders, N. R., Churchyard, T. & Hiddink, J. G., 1 Rhag 2009, Yn: Aquatic Ecology. 43, 4, t. 1193-1199Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Conservation benefits of temperate marine protected areas: variation among fish species.
Blyth-Skyrme, R. E., Kaiser, M. J., Hiddink, J. G., Edwards-Jones, G. & Hart, P. J., 1 Meh 2006, Yn: Conservation Biology. 20, 3, t. 811-820Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Differences in biological traits composition of benthic assemblages between unimpacted habitats
Bolam, S., Garcia, C., Eggleton, J., Kenny, A. J., Buhl-Mortensen, L., Gonzalez-Mirelis, G., van Kooten, T., Dinesen, G., Hansen, J., Hiddink, J., Sciberras, M., Smith, C., Papadopoulou, N., Gumus, A., Van Hoey, G., Eigaard, O. R., Bastardie, F. & Rijnsdorp, A., Mai 2017, Yn: Marine Environmental Research. 126, May 2017, t. 1-13 13 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Ocean community warming responses explained by thermal affinities and temperature gradients
Burrows, M. T., Bates, A. E., Costello, M. J., Edwards, M., Edgar, G. J., Fox, C. J., Halpern, B. S., Hiddink, J. G., Pinsky, M. L., Batt, R. D., Molinos, J. G., Payne, B., Schoeman, D., Stuart-Smith, R. D. & Poloczanska, E. S., 25 Tach 2019, Yn: Nature Climate Change. 9, 12, t. 959-963Allbwn ymchwil: Cyfraniad at gyfnodolyn › Llythyr › adolygiad gan gymheiriaid
- Cyhoeddwyd
Diversity of fishing métier use can affect incomes and costs in small-scale fisheries
Cambie, G., Pantin, J., Lincoln, H., Hiddink, J., Lambert, G. & Kaiser, M., 2017, Yn: Canadian Journal of Fisheries and Aquatic Sciences. 74, 12, t. 2144-2152Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Impact of mangrove forest structure and landscape on macroplastics capture
Cappa, P., Walton, M., Paler, M. K. O., Taboada, E. B., Hiddink, J. G. & Skov, M., Medi 2023, Yn: Marine Pollution Bulletin. 194, Part A, 115434.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Indirect Effects of Bottom Fishing on the Productivity of Marine Fish
Collie, J., Hiddink, J., van Kooten, T., Rijnsdorp, A. D., Kaiser, M., Jennings, S. & Hilborn, R., Gorff 2017, Yn: Fish and Fisheries. 18, 4, t. 619-637Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Extirpation-resistant species do not always compensate for the decline in ecosystem processes associated with biodiversity loss
Davies, T. W., Jenkins, S. R., Kingham, R., Hawkins, S. J. & Hiddink, J. G., 31 Awst 2012, Yn: Journal of Ecology. 100, 6, t. 1475-1481Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Dominance, Biomass and Extinction Resistance Determine the Consequences of Biodiversity Loss for Multiple Coastal Ecosystem Processes
Davies, T. W., Jenkins, S. R., Kingham, R., Kenworthy, J., Hawkins, S. J. & Hiddink, J. G., 7 Rhag 2011, Yn: PLoS ONE. 6, 12, t. e28362Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Detection and quantification of differences in catch rates among research vessel gears and commercial vessels
Delargy, A., Hold, N., Heney, C., Cann, R., Bhandari, K., Colvin, C., Moore, A., Lincoln, H., Hiddink, J. G. & McCarthy, I., 1 Hyd 2022, Yn: Fisheries Research. 254, 106371, 106371.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Differences in demersal community structure and biomass size spectra within and outside the Maltese Fishery Management Zone (FMZ).
Dimech, M., Camilleri, M., Hiddink, J. G., Kaiser, M. J., Ragonese, S. & Schembri, P. J., 1 Rhag 2008, Yn: Scientia Marina. 72, 4, t. 669-682Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- E-gyhoeddi cyn argraffu
Estimating common whelk (Buccinum undatum) abundance using baited remote underwater video (BRUV)
Garratt, M., Bloor, I., Coleman, M., Colvin, C., Hiddink, J. G., Hold, N., Phillips, E., Ward, S. & Jenkins, S., 11 Medi 2024, (E-gyhoeddi cyn argraffu) Yn: ICES Journal of Marine Science.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Estimating the trapping area and density of common whelk (Buccinum undatum) using experimental fishing
Garratt, M., Bloor, I., Coleman, M., Colvin, C., Hiddink, J. G., Hold, N. & Jenkins, S., 1 Ebr 2025, Yn: Fisheries Research. 284, 8 t., 107320.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Species richness in North Atlantic fish: Process concealed by pattern
Gislason, H., Collie, J., MacKenzie, B. R., Nielsen, A., de Fatima Borges, M., Bottari, T., Chaves, C., Dolgov, A. V., Dulcic, J., Duplisea, D., Fock, H. O., Gascuel, D., de Sola, L. G., Hiddink, J. G., ter Hofstede, R., Isajlovic, I., Pall Jonasson, J., Jorgensen, O., Kristinsson, K., Marteinsdottir, G., Masski, H., Matić-Skoko, S., Payne, M. R., Peharda, M., Reinert, J., Sólmundsson, J., Silva, C., Stefansdottir, L., Velasco, F. & Vrgoc, N., Mai 2020, Yn: Global Ecology and Biogeography. 29, 5, t. 842-856Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Mediation of macronutrients and carbon by post-disturbance shelf sea sediment communities
Hale, R., Godbold, J., Sciberras, M., Dwight, J., Wood, C., Hiddink, J. & Solan, M., Medi 2017, Yn: Biogeochemistry. 135, 1-2, t. 121-133Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Predicting the effects of area closures and fishing effort restrictions on the production, biomass, and species richness of benthic invertebrate communities
Hiddink, J. G., Hutton, T., Jennings, S. & Kaiser, M. J., 1 Meh 2006, Yn: ICES Journal of Marine Science. 63, 5, t. 822-830Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Effects of suction-dredging for cockles on non-target fauna in the Wadden Sea.
Hiddink, J. G., 1 Rhag 2003, Yn: Journal of Sea Research. 50, 4, t. 315-323Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Context dependency of relationships between biodiversity and ecosystem functioning is different for multiple ecosystem functions.
Hiddink, J. G., Davies, T. W., Perkins, M., Machairopoulou, M. & Neill, S. P., 1 Rhag 2009, Yn: Oikos. 118, 12, t. 1892-1900Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Implications of Liebig's law of the minimum for the use of ecological indicators based on abundance.
Hiddink, J. G. & Kaiser, M. J., 1 Ebr 2005, Yn: Ecography. 28, 2, t. 264-271Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Active pelagic migrations of the bivalve Macoma balthica are dangerous.
Hiddink, J. G., Kock, R. P. & Wolff, W. J., 1 Meh 2002, Yn: Marine Biology. 140, 6, t. 1149-1156Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Temperature tracking by North Sea benthic invertebrates in response to climate change
Hiddink, J. G., Burrows, M. T. & Molinos, J. G., 1 Ion 2015, Yn: Global Change Biology. 21, 1, t. 117-129Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Abundance and reproduction of Nilsson's pipefish on tidal flats.
Hiddink, J. G. & Jager, Z., 1 Rhag 2002, Yn: Journal of Fish Biology. 61, Supplement A, t. 125-137Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- E-gyhoeddi cyn argraffu
Resource limitation of compensatory responses in ecosystem processes after biodiversity loss
Hiddink, J. G. & Davies, T. W., 7 Awst 2024, (E-gyhoeddi cyn argraffu) Yn: Journal of Applied Ecology.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Seabed trawling’s impact on the climate may be wildly overestimated – new study
Hiddink, J. G., 5 Gorff 2023, The Conversation.Allbwn ymchwil: Cyfraniad at gyhoeddiad arbenigol › Erthygl
- Cyhoeddwyd
Assessing and predicting the relative ecological costs of disturbance to habitats with different sensitivities.
Hiddink, J. G., Jennings, S. & Kaiser, M. J., 1 Ebr 2007, Yn: Journal of Applied Ecology. 44, 2, t. 405-413Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Near disappearance of the Angelshark Squatina squatina over half a century of observations
Hiddink, J. G., Shepperson, J., Bater, R., Goonesekera, D. & Dulvy, N. K., Medi 2019, Yn: Conservation Science and Practice. 1, 9, e97.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Assessing bottom-trawling impacts based on the longevity of benthic invertebrates
Hiddink, J. G., Jennings, S., Sciberras, M., Bolam, S. G., Cambie, G., McConnaughey, R. A., Mazor, T., Hilborn, R., Collie, J. S., Pitcher, C. R., Parma, A. M., Suuronen, P., Kaiser, M. J. & Rijnsdorp, A. D., Mai 2019, Yn: Journal of Applied Ecology. 56, 5, t. 1075-1084Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Indicators of the Ecological Impact of Bottom-Trawl Disturbance on Seabed Communities
Hiddink, J., Jennings, S. & Kaiser, M. J., 1 Tach 2006, Yn: Ecosystems. 9, 7, t. 1190-1199Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Predation on O-group and older year classes of the bivalve Macoma balthica: interaction of size selection and intertidal distribution of epibenthic predators.
Hiddink, J. G., Marijnissen, S. A., Troost, K. & Wolff, W. J., 29 Maw 2002, Yn: Journal of Experimental Marine Biology and Ecology. 269, 2, t. 223-248Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
The effect of habitat and fishing-effort data resolution on the outcome of seabed status assessment in bottom trawl fisheries
Hiddink, J. G., Evans, L., Gilmour, F., Lourenco, G., McLennan, S., Quinn, E. & Shepperson, J., 1 Maw 2023, Yn: Fisheries Research. 259, 106578.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Could our fisheries be more productive? Indirect negative effects of bottom trawl fisheries on fish condition
Hiddink, J. G., Johnson, A. F., Kingham, R. & Hinz, H., 1 Rhag 2011, Yn: Journal of Applied Ecology. 48, 6, t. 1441-1449Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Keeping pace with climate change: what can we learn from the spread of Lessepsian migrants?
Hiddink, J. G., Lasram, F. B., Cantrill, J. & Davies, A. J., 1 Gorff 2012, Yn: Global Change Biology. 18, 7, t. 2161-2172Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Quantifying the carbon benefits of ending bottom trawling
Hiddink, J. G., van de Velde, S. J., McConnaughey, R. A., De Borger, E., Tiano, J., Kaiser, M. J., Sweetman, A. & Sciberras, M., 11 Mai 2023, Yn: Nature. 617, t. E1–E2Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Is sustainable seabed trawling possible? A look at the evidence
Hiddink, J. G., 28 Chwef 2022, The Conversation.Allbwn ymchwil: Cyfraniad at gyhoeddiad arbenigol › Erthygl
- Cyhoeddwyd
Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats
Hiddink, J. G., Jennings, S., Kaiser, M. J., Queiros, A. M., Duplisea, D. E. & Piet, G. J., Ebr 2006, Yn: Canadian Journal of Fisheries and Aquatic Sciences. 63, 4, t. 721-736Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Do haddock select habitats to maximize condition?
Hiddink, J. G., Jennings, S. & Kaiser, M. J., 1 Rhag 2005, Yn: Journal of Fish Biology. 67, Supplement B, t. 111-124Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Using opportunistic data to study the distribution and abundance of a warm water elasmobranch at the northern edge of its range
Hiddink, J. G., Charles, R. & Moore, A., Ion 2024, Yn: ICES Journal of Marine Science. 81, 1, t. 108-118Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Modelling the adaptive value of intertidal migration and nursery use in the bivalve Macoma balthica.
Hiddink, J. G., 30 Ebr 2003, Yn: Marine Ecology Progress Series. 252, t. 173-185Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Can bottom trawling disturbance increase food production for a commercial fish species?
Hiddink, J. G., Rijnsdorp, A. D. & Piet, G., 1 Gorff 2008, Yn: Canadian Journal of Fisheries and Aquatic Sciences. 65, 7, t. 1393-1401Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Predation of intertidal infauna on juveniles of the bivalve Macoma balthica.
Hiddink, J. G., Ter Hofstede, R. & Wolff, W. J., 1 Maw 2002, Yn: Journal of Sea Research. 47, 2, t. 141-159Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Climate induced increases in species richness of marine fishes.
Hiddink, J. G. & Hofstede, R. T., 1 Maw 2008, Yn: Global Change Biology. 14, 3, t. 453-460Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Changes in distribution and decrease in numbers during migration of the bivalve Macoma balthica.
Hiddink, J. G. & Wolff, W. J., 21 Mai 2002, Yn: Marine Ecology Progress Series. 233, t. 117-130Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Global analysis of depletion and recovery of seabed biota following bottom trawling disturbance
Hiddink, J., Jennings, S., Sciberras, M., Szostek, C., Hughes, K., Ellis, N., Rijnsdorp, A. D., McConnaughey, R. A., Mazor, T., Hilborn, R., Collie, J. S., Pitcher, R., Amoroso, R. O., Parma, A. M., Suuronen, P. & Kaiser, M., 1 Awst 2017, Yn: Proceedings of the National Academy of Sciences of the United States of America. 114, 31, t. 8301-8306Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Technical Guidelines for assessing fishing impact from mobile bottom-contacting fishing gears. Version No. 01. ICES Guidelines and Policies - Technical Guidelines. 31 pp.
Hiddink, J. G., 9 Rhag 2024, ICES. 31 t.Allbwn ymchwil: Llyfr/Adroddiad › Adroddiad Comisiwn › adolygiad gan gymheiriaid
- Cyhoeddwyd
Estimating the abundance of benthic invertebrates from trap-catch data
Hiddink, J. G., Coleman, M., Brouwer, S., Bloor, I. & Jenkins, S., Ion 2024, Yn: ICES Journal of Marine Science. 81, 1, t. 86-96 11 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Selection of indicators for assessing and managing the impacts of bottom trawling on seabed habitats
Hiddink, J. G., Kaiser, M. J., Sciberras, M., McConnaughey, R. A., Mazor, T., Hilborn, R., Collie, J. S., Pitcher, C. R., Parma, A. M., Suuronen, P., Rijnsdorp, A. D. & Jennings, S., 1 Gorff 2020, Yn: Journal of Applied Ecology. 57, 7, t. 1199-1209 11 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Importance of fish biodiversity for the management of fisheries and ecosystems.
Hiddink, J. G., MacKenzie, B. R., Rijnsdorp, A., Dulvy, N. K., Nielsen, E. E., Bekkevold, D., Heino, M., Lorance, P. & Ojaveer, H., 1 Ebr 2008, Yn: Fisheries Research. 90, 1-3, t. 6-8Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Bottom trawling affects fish condition through changes in the ratio of prey availability to density of competitors
Hiddink, J., Moranta, J., Balestrini, S., Sciberras, M., Cendrier, M., Bowyer, R., Kaiser, M., Skold, M., Jonsson, P., Bastardie, F. & Hinz, H., Hyd 2016, Yn: Journal of Applied Ecology. 53, t. 1500-1510Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Stable isotopes reveal the effect of trawl fisheries on the diet of demersal target species
Hinz, H., Moranta, J., Balestrini, S., Sciberras, M., Pantin, J. R., Monnington, J., Zalewski, A., Kaiser, M., Skold, M., Jonsson, P., Bastardies, F. & Hiddink, J., 24 Gorff 2017, Yn: Scientific Reports. 7, 6334.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid