Microhabitat‐specific early‐larval survival of the maritime ringlet (Coenonympha tullia nipisiquit)

Abstract

Maritime ringlet butterflies (Coenonympha tullia nipisiquit McDunnough) are rare, endangered salt marsh butterflies with larvae that survive periodic tidal submergence. Only six disjunct populations are known to exist. First-instar larvae were released and monitored in seven microhabitats within a salt marsh in Bathurst, New Brunswick, Canada. From resighting data, microhabitat-specific daily death rates were estimated with maximum likelihood. The survival of the larvae released in groups was compared by calculating minimum number of larvae known to be alive (MNKA). Death rates were low in microhabitats with the larval host plant, salt meadow cordgrass (Spartina patens (Aiton) Muhl.) and the major nectar source, sea lavender (Limonium carolinianum (Walter) Britton), a habitat with a moderate frequency of flooding. Because microhabitats have a large effect on the survival rate of young larvae, use of microhabitat profiles in salt marshes as habitat-quality indices is recommended in critical-habitat assessment and reintroduction efforts. Fig. 1. Microhabitats in the salt marsh at Daly Point, New Brunswick. The larval release sites are indicated as rectangles. Map courtesy of R. P. Webster.

Larval Adaptation of the Endangered Maritime Ringlet <I>Coenonympha tullia nipisiquit</I> McDonnough (Lepidoptera: Nymphalidae) to a Saline Wetland Habitat

“…Although it is possible that the All model coefÞcients were signiÞcant at ␣ ϭ 0.05. a P m , predicted probability of mortality; b 0 , intercept; b n , model coefÞcients; SUB, submergence duration (0 Ð24 h); SP, subspecies (0, inornate ringlet; 1, maritime ringlet). age and growth regimen may have had some effects on the survival of the larvae, both the species effect and the duration effect (Table 2) on survival are very signiÞcant. First-and second-instar larvae of the maritime ringlet had much higher chances of survival on S. patensÐ rich microhabitats in the upper salt marsh than other microhabitats (Sei and Porter 2003). Because tidal submergence exceeding several hours is rare where S. patens grows (Bertness and Ellison 1987), it is unlikely that the prolonged submergence affects larval survival in their natural habitat.…”

“…Maritime ringlet larvae experience periodic seawater submergence in their natural habitats, where they feed on the major host plant, salt meadow cordgrass, Spartina patens (Aiton) Muhl. (Webster 1998, Sei andPorter 2003). Given the prevalence of suitable salt marshes in the Bay of Chaleurs region, rarity of the maritime ringlet makes one suspect that it has low potential for recolonization after local extinction events.…”

“…Maritime ringlet larvae seem to have narrow microhabitat requirements within a salt marsh (Sei and Porter 2003). Although most of the microhabitats support potential host plants (e.g., Spartina spp., Distichlis spicata L. Greene, Festuca rubra L.), the larvae had the highest survival rate in microhabitats dominated by S. patens with moderate ßooding duration.…”

Delimiting species boundaries and the conservation genetics of the endangered maritime ringlet butterfly (Coenonympha nipisiquitMcDunnough)

“…2004; but see Reed & Frankham 2001). However, C. nipisiquit remains vulnerable to environmental stochasticity (Sei & Porter 2003) because its low habitat connectivity precludes the dynamics of traditional metapopulation structure (Hanski & Simberloff 1997), and its habitat is subject to fairly common natural disturbance (Roberts & Robertson 1986; Jacobson & Jacobson 1987), sea‐level rise (Warren & Niering 1993) and pressure of development in the areas surrounding its habitat.…”

“…It feeds mainly on the salt‐meadow cordgrass, Spartina patens (Aiton) Muhl. (Webster 1998), experiences periodical flooding during high tides, and has narrow requirements for larval microhabitats within a salt marsh (Sei & Porter 2003; Sei 2004). In contrast, the inornate ringlet ( C. inornata Edwards) is a common and widespread taxon throughout the northeastern United States and southeastern provinces of Canada that inhabits upland and wet meadows, and uses various grasses as hosts (Davenport 1941; Brown 1955).…”