Determining the life history strategy of the cryptobenthic reef gobies Coryphopterus hyalinus and C. personatus

Abstract

Understanding the life history strategy of species can clarify their functional role, and contribution to the productivity and resilience of an ecosystem. We use otolith microstructure analysis to study the life history of 2 widespread and abundant Caribbean reef fishes, genetically identified here as the glass goby Coryphopterus hyalinus and masked goby C. personatus. Our analysis reveals that these species exhibit an extreme life history relative to other vertebrates due to their short lifespan, small adult body size, early maturity, and continuous growth in body length throughout reproductive age. We find that pelagic larval duration (PLD) varies widely, and average larval growth influences PLD where faster-growing larvae have shorter PLDs. We show that average daily growth substantially decreases during the settlement transition to reef habitat, approximately coinciding with reproductive maturity. Continuous somatic growth throughout reproductive age can serve to support greater fecundity in older, larger-bodied females and enhance survivorship. Several features of the ecology (i.e. broad depth range, planktivorous diet) and life history (i.e. small adult body size, quick generational turnover, short lifespan) of C. hyalinus and C. personatus indicate that they play a key trophic role in transferring nutrients from pelagic plankton to Caribbean reef predators and the reef benthos. Our analyses highlight why life history traits related to survival, reproduction, and population dynamics can enhance our understanding of ecosystem-scale processes and functioning on coral reefs.

Life‐history constraints, short adult life span and reproductive strategies in coral reef gobies of the genus Trimma

“…Small body size comes with many constraints including a short life span, high mortality risk, a long PLD relative to life span and, consequently, a short reproductive life. Because the age of coral reef fishes ranges from 59 days in Eviota sigillata (Depczynski & Bellwood, 2006 ) to 81 years in Macolor macularis (Taylor et al ., 2021 ), Trimma were at the lower end of the spectrum, which is also seen in other small CRFs ( e.g ., Beeken et al ., 2021 ; Depczynski et al ., 2007 ; Longenecker & Langston, 2005 ). Consequently, the maximum window available for reproduction is very narrow.…”

“…The PLDs of the three Trimma species examined represented a substantial proportion of their maximum life span (>25%), which is high, compared with the <1% demonstrated by many larger coral reef fishes (Depczynski & Bellwood, 2006 ). Yet, spending over a quarter of the life span as pelagic larvae is not unique to Trimma and is seen in other CRFs such as the genera Coryphopterus (Beeken et al ., 2021 ), Eviota (Depczynski & Bellwood, 2006 ) and Enneapterygius (Longenecker & Langston, 2005 ). An extensive PLD to allow growth to a sufficient size may be a strategy to decrease extreme mortality of small recruits (Beeken et al ., 2021 ).…”

“…Yet, spending over a quarter of the life span as pelagic larvae is not unique to Trimma and is seen in other CRFs such as the genera Coryphopterus (Beeken et al ., 2021 ), Eviota (Depczynski & Bellwood, 2006 ) and Enneapterygius (Longenecker & Langston, 2005 ). An extensive PLD to allow growth to a sufficient size may be a strategy to decrease extreme mortality of small recruits (Beeken et al ., 2021 ). Some fishes that settle into protective habitats with lower post‐settlement mortality have a reduced PLD (Depczynski & Bellwood, 2006 ).…”

“…By contrast, the pygmy goby, Trimma nasa , lives <90 days and has a PLD of 34 days, representing 38.7% of its life span (Winterbottom & Southcott, 2008 ). PLD may be constrained among fishes to attain a critical size or developmental stage before settlement onto the reef (Beeken et al ., 2021 ; Depczynski & Bellwood, 2006 ). Consequently, PLD, which is a significant time in early life not available for reproduction, potentially makes up a large proportion of the maximum life span of CRFs.…”

Examining the diversity, stability and functioning of marine fish communities across a latitudinal gradient

“…Specifically, small, bottom‐dwelling [‘cryptobenthic’ (Brandl et al, 2018; Depczynski & Bellwood, 2003)] fishes form diverse communities of native species across dock pilings in the western Atlantic and show the predictable latitudinal diversity gradient from Panama to Maine (Brandl et al, 2017). Due to the short life spans (Beeken et al, 2021; Depczynski & Bellwood, 2006), steady recruitment (Lefèvre & Bellwood, 2015), and high site fidelity of cryptobenthic fishes (Brandl et al, 2018, 2019), these communities represent a tractable system for manipulative work on vertebrate assemblages, which remain relatively understudied, and present a promising opportunity to empirically test macroecological patterns relating to the role of biodiversity for stability and ecosystem functioning.…”