In situ estimates of larval development and mortality in the New Zealand sea urchin Evechinus chloroticus (Echinodermata:Echinoidea)

Abstract

Synchronous spawning of the sea urchin Evechinus chloroticus Valenclennes in a closed fiord population (Doubtful Sound, New Zealand) provlded a unique opportunity to calculate in a t u rates of larval mortality and development. The resulting cohort of larvae was sampled 7 d after this spawning, and subsequently every 2 wk at 5 sites throughout the fiord. Instantaneous mortality rates for E. chloroticus larvae were calculated using 3 different models. Mortality (M) was found to be constant and estimated at M = 0.164, 0.173, and 0.085 d-' for the 3 models; the most accurate estimate of mortality probably being M = 0.164 d-l. Larvae reach competency in Doubtful Sound between 18 and 31 d. which is 1.05-to 1.82-fold slower than maximum growth rates recorded in laboratory cultures. Larvae spent most of their development time (44.9%) as 4-armed plutei, and only a small proportion of these larvae (11.5 %) survived beyond this stage We suggest that the slower in s~t u larval development rate and the accumulat~on of larvae in the 4-armed pluteus stage indicate that these larvae are foodhmited in the plankton. Given the high daily mortality rate, these food-limited early pluteus larvae may be a cntlcal life history stage for E chloroticus populations in Doubtful Sound.

DNA photorepair in echinoid embryos: effects of temperature on repair rate in Antarctic and non-Antarctic species

“…Metabolic rates in Antarctic embryos are very low (Peck, 2002), with respiration orders of magnitude lower than in temperate counterparts (Hoegh-Guldberg et al, 1991). Growth rates and developmental times are similarly slower at lower temperatures (Clarke, 1992), with time to complete development ranging from 115·days in Sterechinus (Bosch et al, 1987), 30-60·days in Evechinus (Lamare and Barker, 1999) and 42·days in Diadema setosum (Onoda, 1936;Mortensen, 1937). Slow physiology as a general feature of Antarctic invertebrate embryos has been attributed to both low temperatures and nutrient constraints (low phytoplankton concentrations).…”

Variation in sunscreen compounds (mycosporine‐like amino acids) for marine species along a gradient of ultraviolet radiation transmission within doubtful sound, New Zealand

“…For example, Evechinus has a long-lived (30-60 days) planktotrophic embryonic and larval stage that is relatively small (100-1000 µm) and transparent (Lamare & Barker 1999). These embryos represent a key life-history stage undergoing rapid DNA replication, and they can be sensitive to UV-R Lesser & Barry 2003).…”

“…E. chloroticus is known to spawn in Doubtful Sound between December and April (Lamare 1999;Lamare et al 2002) depending on location. Measures of gonad index during this research failed to identify a clear spawning period (where index increases and then decreases pre-to post-spawning respectively).…”

Stage-specific distribution of barnacle larvae in nearshore waters: potential for limited dispersal and high mortality rates

“…More direct approaches based on in situ tracking and intensive sampling of planktonic aggregations have been attempted for larval crustaceans (e.g. Natunewicz et al 2001), bivalves (Arnold et al 2005), and echinoderms (Lamare & Barker 1999), and provided valuable information on the scales and processes that may shape the distribution of larvae relative to their parental populations.…”

“…Although such tracking may be feasible in closed or semi-enclosed environments (e.g. Lamare & Barker 1999), in open coastal waters it requires observations of plankton distribution at spatial and temporal scales that are seldom achieved (but see Natunewicz et al 2001). Thus, laboratory (Johnson & Brink 1998) and indirect field methods are usually employed to estimate mortality from ratios of local larval production to recruitment (e.g.…”