Invasions by dreissenid mussels and the round goby have altered the makeup of benthos in many areas of the Great Lakes complicating the use of benthic invertebrate composition as an indicator of environmental conditions. The Ontario Ministry of the Environment, Conservation and Parks (MECP) has been monitoring the composition of benthos at nearshore stations since the 1990s. The interactive influences of environmental change and invasive species have been evident in areas of the Toronto Waterfront such as Humber Bay (HB), an area of intensifying urbanization. Dreissenid mussels were first detected in HB in 1994, became abundant in 2000, and were followed by the round goby in 2005. Both invasions overlapped with increasing population density in the watershed and efforts to reduce pollutant and nutrient inputs. Benthic invertebrate diversity increased post-dreissenids, with densities of gastropods and amphipods increasing during peak mussel abundance (2000–2003). Dreissenid abundance declined after 2005, and snails (Valvatidae) disappeared, corresponding with increasing goby abundance. Abundance of sphaeriid clams declined over the monitoring period. Water clarity increased and the chlorophyll a level declined in the mid-1990s, before dreissenids were abundant at the site. Trophic conditions inferred from invertebrate composition shifted from oligotrophic in 1990 to mesotrophic and back to oligotrophic in 2012. There was little change in sediment quality other than a subtle increase in clay and fine silt at the primarily silty site. The trajectory of changes in the benthos was more strongly correlated with the dreissenid and goby invasions than changes in environmental quality.

苔藓类贻贝和圆形虾虎鱼的入侵改变了五大湖许多地区的底栖动物组成，使底栖无脊椎动物成分作为环境状况的指标变得更加复杂。自1990年代以来，安大略省环境，自然保护和公园部（MECP）一直在监测近岸站底栖动物的成分。环境变化和入侵物种之间的互动影响在多伦多海滨地区（如亨伯湾（HB）），城市化进程日趋明显。Dreissenid贻贝于1994年在HB中首次被发现，在2000年变得丰富，随后在2005年被圆环虾虎鱼捕捞。这两种入侵都与流域人口密度的增加以及减少污染物和养分输入的努力重叠。在贻贝高峰期（2000-2003年），底栖动物的无脊椎动物多样性增加，腹地类动物和两栖动物的密度增加。2005年以后，Dreissenid的丰度下降了，蜗牛（Valvatidae）消失了，与虾虎鱼的丰度增加相对应。在监测期内，鳞翅类蛤的数量减少了。水的透明度增加，叶绿素增加一个水平在90年代中期有所下降，dreissenids是在现场丰富了。由无脊椎动物组成推断出的营养条件从1990年的低营养状态转变为中营养，2012年又恢复为低营养状态。除了主要粉质部位的粘土和细粉土略有增加外，沉积物质量几乎没有变化。与环境质量的变化相比，底栖动物的变化轨迹与藻类和虾虎鱼的入侵更密切相关。