Copepod feeding in a coastal area of active tidal mixing: diel and monthly variations of grazing impacts on phytoplankton biomass

Abstract

This study examined monthly feeding rates and grazing impact on phytoplankton biomass, as well as diel feeding rhythms of four key copepod species in a tidally well mixed estuary (Asan Bay, Korean Peninsula). Monthly ingestion rates estimated based on gut pigment analysis were closely associated with their peak densities, but not with phytoplankton biomass, implying high ingestion may be related to reproductive output for population growth. The three smaller copepods, Acartia hongi, Acartia pacifica and Paracalanus parvus, showed feeding preference for smaller phytoplankton (<20 μm) with higher clearance rates, whereas the larger Calanus sinicus preferred larger phytoplankton. Acartia pacifica and P. parvus showed distinct increased nocturnal feeding rates as measured with gut fluorescence, whereas A. hongi showed no significant day–night differences. Copepod diel feeding patterns were not associated with food quantity, and endogenous physiological rhythm might be hypothesized as responsible for the observed diel feeding patterns. Grazing impact on phytoplankton biomass by the four copepods in the estuary was on average 8% (range 0.2–29.8%) of the phytoplankton standing stock, similar to values reported in other coastal waters. Very high copepod abundances but low daily carbon ration (<20% for all copepods) provided by feeding on phytoplankton indicate that copepods also grazed on other non‐phytoplankton foods in Asan Bay.

Spreading factors of a globally invading coastal copepod

“…However, in this case, the introduction of P. marinus by means of ballast waters or by attachment to ship hulls must be excluded because the lake is shallow and non-navigable, but could be due to aquaculture, which is extensively carried out in the lake. In Lake Faro, P. marinus follows the same seasonal cycles recorded in its original sites (e.g., Liang & Uye, 1997a; Lee et al, 2012), with a major peak of abundance in June-July (~4 × 10 3 ind. m -3…”

Response to salinity and temperature changes in the alien Asian copepod Pseudodiaptomus marinus introduced in the Black Sea

“…According to the review by Sabia et al (), P. marinus flourishes at salinities ranging from 30.0 to 37.0 psu, although showing a salinity window from 2.5 to 38.0 psu. In its native region, moreover, P. marinus is strongly thermophilic (Lee, Song, Park, & Choi, ; Uye, Iway, & Kasahara, ), although it has been found also at lower temperatures outside its optimal range (Brylinski et al, ; Deschutter et al, ).…”

“…In its native region, moreover, P. marinus is strongly thermophilic (Lee, Song, Park, & Choi, 2012;Uye, Iway, & Kasahara, 1982), although it has been found also at lower temperatures outside its optimal range (Brylinski et al, 2012;Deschutter et al, 2018).…”

Impacto alimentario de los copépodos calanoideos en el Océano Pacífico colombiano

“…Este método cuantifica la tasa de ingestión, a partir de la tasa de evacuación (k) y el contenido de pigmentos entéricos (G) en los individuos. Si se asume que las tasas de ingestión son similares en los individuos que tienen similar tamaño y se encuentran bajo condiciones ambientales similares (Morales et al,1990;, entonces a partir de esta información y el estimado de abundancia del zooplancton herbívoro de una localidad se puede establecer el impacto alimentario total (Dagg, 1995 Lee et al, 2012). En el presente trabajo se cuantifica el impacto alimentario que ejercen los copépodos sobre el fitoplancton en el Océano Pacífico colombiano, considerando el aporte proporcional de tres fracciones de tamaño, generándose información novedosa sobre uno de los procesos oceanográficos menos estudiados en esta región.…”