Effects of Low Salinity on Adult Behavior and Larval Performance in the Intertidal Gastropod Crepipatella peruviana (Calyptraeidae)

Abstract

Shallow-water coastal areas suffer frequent reductions in salinity due to heavy rains, potentially stressing the organisms found there, particularly the early stages of development (including pelagic larvae). Individual adults and newly hatched larvae of the gastropod Crepipatella peruviana were exposed to different levels of salinity stress (32(control), 25, 20 or 15), to quantify the immediate effects of exposure to low salinities on adult and larval behavior and on the physiological performance of the larvae. For adults we recorded the threshold salinity that initiates brood chamber isolation. For larvae, we measured the impact of reduced salinity on velar surface area, velum activity, swimming velocity, clearance rate (CR), oxygen consumption (OCR), and mortality (LC50); we also documented the impact of salinity discontinuities on the vertical distribution of veliger larvae in the water column. The results indicate that adults will completely isolate themselves from the external environment by clamping firmly against the substrate at salinities ≤24. Moreover, the newly hatched larvae showed increased mortality at lower salinities, while survivors showed decreased velum activity, decreased exposed velum surface area, and decreased mean swimming velocity. The clearance rates and oxygen consumption rates of stressed larvae were significantly lower than those of control individuals. Finally, salinity discontinuities affected the vertical distribution of larvae in the water column. Although adults can protect their embryos from low salinity stress until hatching, salinities <24 clearly affect survival, physiology and behavior in early larval life, which will substantially affect the fitness of the species under declining ambient salinities.

The influence of season and the tidal cycle on division of labour by the radula during feeding in the estuarine brooding gastropod Crepipatella dilatata (Calyptraeidae)

“…Under these conditions the mantle cavity is sealed from the external environment, suspension-feeding ceases and there is no production of a mucous cord. This behaviour has been recorded previously for C. dilatata by Montory et al [49] and for C. peruviana and the oyster Ostrea chilensis by Chaparro et al [17]. The difference in the critical salinity between females [23] and males [19] may be attributable to the fact that larval stages of marine invertebrates are often more sensitive than adults to low salinity [50][51][52][53].…”

“…Under these conditions salinity can decrease well below the critical value of 22-23 at which the female responds by isolating the mantle cavity from the external environment, thereby protecting the soft tissues and the embryos (in the case of brooders) from osmotic stress [17,49,50,54]. Suspension-feeding ceases, and the very low rates of exclusion of the radula for removal of material from the food pouch may represent the arrival in the food pouch of residual particles in the mantle water and/or particles in the mantle tracts, or the use of material accumulated in the food pouch before isolation of the mantle cavity.…”

Complexity of the prey spectrum ofAgaronia propatula(Caenogastropoda: Olividae), a dominant predator in sandy beach ecosystems of Pacific Central America

“…Much of the Pacific Central American coast experiences a pronounced contrast between a rainy and a dry season. Frequent torrential rains during the wet season could certainly induce severe hypo-osmotic stress for any osmo-conforming invertebrate that utilizes the intertidal zone at intermediate and low tide (for studies of the effect in other taxa, see Blockley et al, 2007 ; Morritt et al, 2007 ; Montory et al, 2014 ). Mazatlania fulgurata , a columbellid gastropod that shares the habitat with A. propatula , reproduces primarily in the dry season, which probably reduces the chance of exposure of eggs and larvae to hypo-osmotic stress (D. Stevenson & W. S. Peters, 2012–2018, unpublished data).…”

The filter‐feeding bivalve Mytilus chilensis capture pelagic stages of Caligus rogercresseyi: A potential controller of the sea lice fish parasites

“…Following the methodology described by Bradley, Strickler, Buskey, and Lenz (), Jian and Kiørboe (), Montory, Pechenik, Diederich, and Chaparro () and Svetlichny, Larsen, and Kiørboe (), we estimate swimming and resting activity of C. rogercresseyi larvae. Twenty nauplius II larvae of C. rogercresseyi were placed individually in Petri dishes of 150 mm in diameter and with a graduate scale etched onto the base (Chaparro et al, ) and filled with sea water as described above.…”