Growth of juvenile Atlantic menhaden, Brevoortia tyrannus (Pisces: Clupeidae) in MERL mesocosms: Effects of eutrophication

Abstract

Growth and mortality of recently hatched Atlantic menhaden (Brevoortia tyrunnus) were examined for 7 months under two levels of nutrient enrichment (with and without silicate enhancement) and control conditions in experimental marine mesocosms (13 m3). Results from six plankton-dominated systems confirmed the often hypothesized but rarely demonstrated link between nutrient loading, food quantity, and growth in marine fish. Weekly abundance and mortality were not significantly different (P z 0.05) between controls and treatment mesocosms. On the other hand, von BertalanfIy’s growth coefficients and mean asymptotic sizes of juvenile Atlantic menhaden were significantly different (P < 0.05), with highest values in the two silicate-enhanced systems, intermediate values in the nutrient-addition tanks, and lowest values in the two control systems. Growth and size were significantly (P < 0.05) and positively correlated (rz = 0.98) with mean food availability (measured as the sum of phytoplankton plus zooplankton carbon), which in turn was significantly (P < 0.05) and positively correlated (r2 = 0.94) with nutrient loading (measured as the input of N+P+Si).