Full of eggs and no place to lay them: hidden cost of benthic development

Abstract

The scarcity of sites suitable for attaching eggs may be a hidden cost to depositing embryos in benthic aggregations. We tested this hypothesis with the bubble-shell snail Haminaea vesicula, which lives on mud or sand but requires firm substrata for attaching its eggs. In pools on a sandflat where firm substrata were scarce, the preferred substrata were but a small fraction of the total available firm substrata. Abundant drifting green algal blades comprised 1 to 11% cover but were rarely used for egg deposition. Substrata commonly used for egg deposition totaled less than 1% cover, and included attached and drifting eelgrass, drifting branched red algae, bivalve shells, and attached green algal blades. In choice experiments, the snails preferred to deposit eggs on branched red algae and eelgrass, with bivalve shells next and green algal blades last. To test the hypothesis that substratum availability limits egg deposition, we added artificial eelgrass made of duct tape to tidepools inhabited by the snails. The mean number of egg ribbons laid m -2 in the experimental areas was 20 to 360 times that in control areas, and the mean number of adult snails present and egg ribbons per adult snail were greater in the experimental areas. Also, more egg ribbons per adult were deposited on artificial eelgrass when it was positioned away from natural eelgrass patches, indicating that distances of a few meters affect availability of substrata for deposition. The results imply that in this habitat the snails travel to scarce substrata for egg deposition, with whatever costs in time, energy, or risk that may be associated with travel. Scarcity of suitable sites for benthic egg masses can limit an apparently safe mode of development. Habitats that regularly support adult populations can differ greatly in suitability for egg deposition, but this limitation may not be apparent without experimental intervention. KEY WORDS: Benthic · Deposition site · Development · Egg deposition · Egg mass · Substratum selectionResale or republication not permitted without written consent of the publisher

A field experiment demonstrating risk on the seafloor for planktonic embryos

“…Aggregating embryos creates the problem of a concentrated consumption of oxygen with a limited surface area for its supply, but the geometry of the egg masses enhances supply of oxygen (Lee and Strathmann ; Moran and Woods , ). The maternal placement of egg masses can also enhance oxygen supply (Fernandes and Podolsky ), and enhance protection from predators (Shimek ) and other hazards (Biermann et al ; Przeslawski ), although maternal choices for safe sites are often limited (Spight ; Wilson ; Von Dassow and Strathmann ).…”

Predator-induced plasticity in egg capsule deposition in the mud snail Tritia obsoleta

“…For comparison, the bubble-shell snail, Haminaea vesicula, also preferentially deposits on 328 eelgrass and when artificial eelgrass was provided in a field experiment, laying dramatically 329 increased both in sum and on a per-capita basis (von Dassow & Strathmann 2005). We did not 330 collect data on whether the per-capita abundance of egg capsules increased in T. obsoleta, but 331 did find that snails were attracted to and began laying on transplanted eelgrass in areas where it 332 was absent or low in abundance.…”

Field Monitoring of Tritia mutabilis (Linnaeus, 1758) Egg Capsule Deposition and Intracapsular Embryonic Patterns Using Artificial Substrates and Machine Learning-Based Approaches

“…Many marine invertebrates, mostly gastropod families, enclose their fertilized eggs within capsules that play a protective role in the embryo defense against adverse environmental factors (Pechenik, 1983;Rawlings, 1994Rawlings, , 1999von Dassow and Strathmann, 2005;Przeslawski and Davis, 2007). Egg capsules are attached to hard substrates including submerged gear used for small-scale fishing and waste materials (Grati et al, 2018;Kaviarasan et al, 2020;Ganias et al, 2021).…”

“…Given the energetic cost of capsule production in these organisms (Rawlings, 1999), the availability of adequate substrates for oviposition represents a major determinant of reproductive output of a population. In fact, species living in marine soft-bottom environments with limited availability of hard substrates must adopt different oviposition strategies such as attaching their egg capsules to living organisms (e.g., algae or bivalves; von Dassow and Strathmann, 2005;Carrasco and Phillips, 2014;Aguilar et al, 2017;Corte et al, 2019). Communal egg-laying is one of the most frequent behavior observed in several neogastropod species (Carrasco and Phillips, 2014).…”