New records of the amphipods Gammarus tigrinus Sexton, 1939 and Pontogammarus robustoides G.O. Sars, 1894 in Latvian waters of the Baltic Sea.
The paper presents recent records of the North-American amphipod Gammarus tigrinus and the Ponto-Caspian amphipod Pontogammarus robustoides in Latvian territorial waters of the Baltic Sea. P. robustoides was found for the first time in shallow waters of the Gulf of Riga near Jurmala City in June 2009. During field surveys of 2011-2012, P. robustoides and another invader, the North-American amphipod G. tigrinus (detected earlier in Estonian part of the Gulf), were recorded in different sites of the Latvian waters of the Gulf of Riga and in the coastal Lake Liepaja. Abundance ranged between 1-70 ind./m2 for P. robustoides and 5-100 ind./m2 for G. tigrinus, suggesting they potential role in the functioning of the benthic community in near future.