Effects of temperature and food availability on adult body length in natural and laboratory populations of Paracerceis sculpta (Holmes), a Gulf of California isopod
Sm. Shuster et Ee. Guthrie, Effects of temperature and food availability on adult body length in natural and laboratory populations of Paracerceis sculpta (Holmes), a Gulf of California isopod, J EXP MAR B, 233(2), 1999, pp. 269-284
Citations number
43
Categorie Soggetti
Aquatic Sciences
Journal title
JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY
In the Gulf of California, Paracerceis sculpta (Holmes), a sphaeromatid iso
pod, feeds on coralline algae and breeds in the spongocoels of calcareous s
ponges (Leucetta losangelensis de Laubenfels). Near Puerto Penasco, Sonora,
sea surface temperature and algal abundance fluctuate throughout the year.
To investigate how these factors influence isopod growth, we plotted the b
ody lengths of field-collected isopods against monthly sea surface temperat
ures, as well as against the relative abundance of coralline algae (Coralli
na; Amphiroa), over a 26-month period (1983-1985). We found that average bo
dy lengths of the four adult morphs in this species (alpha-, beta-, gamma-m
ales and females), were larger in cool months and smaller in warm months. O
ur records of female reproductive condition at capture allowed identificati
on of the approximate dates on which females matured, thus the effect of te
mperature on growth was most clearly seen in females. Monthly average body
lengths correlated negatively with temperature for all adult morphotypes, w
ith different slopes and intercepts; morphotypes undergoing more molts had
steeper slopes. Coralline algae abundance showed no seasonal patterns, and
we found no significant relationships between relative algal abundance and
isopod body length for any adult morph. In the laboratory, animals reared a
t lower temperature (21 degrees C) matured at larger body lengths than indi
viduals reared at higher temperatures (27-30 degrees C). However, well-fed
individuals grew no more rapidly than poorly-fed individuals. Thus, variati
on in food availability had no recognizable effect on isopod growth in eith
er the laboratory or in the field, whereas variation in temperature signifi
cantly influenced growth in both locations, with effects proportional to th
e number of pre-adult molts. (C) 1999 Elsevier Science B.V. All rights rese
rved.