Growth production of the euphausiid Nyctiphanes simplex on the coastal shelf off Bahía Magdalena, Baja California Sur, México

Abstract

ABSTRACT. Growth production of the euphausiid Nyctiphanes sirnplex Hansen was examined off the southwest coast of the peninsula of Baja California, Mexico (Bahia Magdalena, 24 to 25" N ) , as a function of seasonal changes of temperature, zooplankton biomass, upwelling index, and regional ocean circulation. The data were collected during 4 oceanographic surveys from June to November 1986. High densities of N. sirnplex were found in the shallow coastal waters (c300 m). High production is maintained during late spring and summer, decreasing during autumn when stratification of the water column develops. We estimate the production attributable to growth of N. sirnplex on the coastal shelf was 273.42 mg m-? yr.' and showed a strong seasonal variation. This value was about '4 the value previously reported at

Latitudinal changes of euphausiid assemblages related to the morphological variability of the sound scattering layer along Baja California, October 1994

“…These latitudinal trends are reasonably constant unlike the diel variability observed in the SSLs appearance caused by the 24-h vertical migration reported by Robinson and Gómez-Gutiérrez (1998). Latitudinal changes in N. simplex growth production was reported by Gómez-Gutiérrez et al (1996), supporting the idea that the southern region is less productive than northern ones, and the SSLs are less dense and smaller along the southern part of Baja California. Estimations of the standing stock expressed as the carbon content of three of the most abundant euphausiid species indicate that the northern area is at least four times more productive than the southern area, showing different productivity between these two environments.…”

“…Along the west coast of Baja California, a strong latitudinal environmental gradient occurs during autumn (Gómez-Gutiérrez et al, 1996, Gómez-Gutiérrez andRobinson, 1997). Because it is known that zooplankton assemblages have latitudinal changes along Baja California during this season (i. e. Brinton, 1962Brinton, , 1979Gómez-Gutiérrez et al, 1995, Gómez-Gutiérrez andRobinson, 1997), an interesting comparative study can be performed of the aggregation behavior of the SSLs of temperate and tropical epipelagic assemblages.…”

Seasonal growth, molt, and egg production rates of Nyctiphanes simplex (Crustacea: Euphausiacea) juveniles and adults in the Gulf of California

“…All previous information about Nyctiphanes simplex biomass productivity, and therefore its vital rates, was deduced from preserved specimens (Lavaniegos 1995, Gómez-Gutiérrez et al 1996, De Silva-Dávila & Palomares-García 1998, De SilvaDávila et al 2002. The same approach was used to estimate biomass production for the other 3 Nyctiphanes species around the world (Lindley 1982, Ritz & Hosie 1982, Hosie & Ritz 1983, Barange & Stuart 1991.…”

“…Multiple studies have estimated Nyctiphanes simplex biomass production rates along the west coast of Baja California peninsula (Lavaniegos 1995, Gómez-Gutiérrez et al 1996, De Silva-Dávila et al 2002 and in La Paz Bay (southwestern Gulf of California; De Silva-Dávila & Palomares-García 1998). However, all these studies estimated N. simplex productivity using only preserved specimens without any direct measurements of vital rates.…”

Tidal current transport of epibenthic swarms of the euphausiid Nyctiphanes simplex in a shallow, subtropical bay on Baja California peninsula, México

“…Contrary to our expec-tations, when we used a submarine video camera, a scientific echosounder, and a zooplankton net in this present study, we discovered that dense epibenthic swarms of adult N. simplex commonly enter through a relatively shallow (28 to 50 m depth) section of the main mouth of this subtropical bay. Gómez-Gutiérrez (1995) and Gómez-Gutiérrez et al (1996) reported that the abundance, population structure, and secondary production of Nyctiphanes simplex over the continental shelf of Bahía Magdalena demonstrates the formation of dense swarm densities in spring and summer (average 1075 and 2520 ind. ) when the water column is warmer, well mixed, and contains low phytoplankton concentration because of the retreat of the CC toward the north.…”