Effects of suspended sediment on survival, growth, and nutritional condition of green-lipped mussel spat (Perna canaliculus, Gmelin, 1791)

Abstract

Suspended sediment is a significant current threat to coastal ecosystems in many parts of the world. Sediment runoff into the ocean is increasing due to numerous human activities, such as agriculture, deforestation, construction, and mining. Additionally, climate change is impacting local weather patterns, with many regions experiencing marked changes in the frequency and extent of precipitation. Extreme weather events, such as cyclones, can increase suspended sediment (SS) in coastal waters by up to 100-fold. This rapid change in SS can negatively affect filter-feeding bivalves by diminishing their feeding efficiency, often preventing feeding until the sediment settles. In New Zealand, juveniles of the green-lipped mussel (Perna canaliculus) have rudimentary structures for capturing and sorting food particles from the seston, which are prone to clogging and damage. In this study, the effects of a range of SS concentrations (0–1250 mg L⁻¹) on the survival, growth, and nutritional condition of juvenile green-lipped mussels (1–2 mm SL) were determined over two time scales (5 and 30 days) in controlled laboratory experiments. Neither mortality nor nutritional condition were impacted by SS. However, the presence of SS positively affected growth (p < 0.05) and mussel settlement location (p < 0.01) at both time scales. The results show that, under these conditions, SS levels ≤1250 mg L⁻¹ are not apparently harmful to P. canaliculus spat and may even be advantageous.